Occlusal and Functional Improvement of Patients With Midfacial Hypoplasia Corrected Using Intraoral Tooth-Borne Mid-Maxillary Osteodistractors at Teaching Hospital-Karapitiya, Sri Lanka

Objective: Mid-maxillary osteodistraction (MMOD) is a novel technique. This study seeks to assess the occlusal and functional improvement of patients with midfacial hypoplasia secondary to cleft lip and palate. Design: This was done as a retrospective study at the Regional Cleft Centre of the Teaching Hospital-Karapitiya (THK). Participants: A total of 81 patient records were accessed on those who underwent MMOD with a tooth-borne intraoral device from January 1, 2007, to December 31, 2016, at THK. Methods: Records of the patients included pre- and post-treatment lateral cephalograms, study models, speech assessments, and photographs. Results: An advancement ranging from 5 to 12 mm (mean, 8.14 mm) was achieved in all patients; 80% (n = 63) and 87.65% (n = 71) showed improvement in consonant production and quality of speech. These were statistically significant (P < .05). With regard to the Peer Assessment Rating score assessing the occlusal improvement, 97.6% showed an improvement whereas only 2 patients showed no improvement. There was a significant improvement in sella (S), nasion (N), and point A (SNA) angle; point A, the nasion, and point B (ANB) angle; and the maxillary length over the treatment period (P < .05). The change in the ANB angle and maxillary length significantly differed between genders with males having a comparatively higher improvement. The profile improvements were noteworthy on the profile photographs. Conclusion: This relatively novel approach to maxillary advancement by maxillary distraction using a combined surgical and modified orthodontic technique has proven to be successful. This protocol and the technique have improved function, occlusion, and the aesthetics.

Surgical Videos with Synchronised Vertical 2-Split Screens Recording the Surgeons' Hand Movement

Purpose: To improve the state-of-the-art teaching system by creating surgical videos with synchronised vertical 2-split screens. Methods: An ultra-compact, wide-angle point-of-view camcorder (HX-A1, Panasonic) was mounted on the surgical microscope focusing mostly on the surgeons' hand movements. In combination with the regular surgical videos obtained from the CCD camera in the surgical microscope, synchronised vertical 2-split-screen surgical videos were generated with the video-editing software. Results: Using synchronised vertical 2-split-screen videos, residents of the ophthalmology department could watch and learn how assistant surgeons controlled the eyeball, while the main surgeons performed scleral buckling surgery. In vitrectomy, the synchronised vertical 2-split-screen videos showed the surgeons' hands holding the instruments and moving roughly and boldly, in contrast to the very delicate movements of the vitrectomy instruments inside the eye. Conclusions: Synchronised vertical 2-split-screen surgical videos are beneficial for the education of young surgical trainees when learning surgical skills including the surgeons' hand movements.

Studies on Influence of Tunnel Surrounding Rock Stability Analysis Based on Material Yield Criterions

Numerical simulation is one of main methods for tunnel surrounding rock stability analysis. By now, there hasn’t be unanimous view on that what kind of yield criterion is adopted for different surrounding rock class and different buried depth. Mohr-Coulomb yield criterion is always adopted abroad, Drucker-Prager yield criterion is always adopted in China, moreover, the principles are different when adopting D-P yield criterion at home and abroad. Based on introducing the Mohr-Coulomb yield criterion and D-P yield criterions, this paper uses the M-C exterior angle point of circle criteria, which is popular in the international arena for the D-P yield criterion, and finds parameters of geotechnical material for D-P yield criterions through the parameter transformation. Combining with 3D elastic-plastic finite element simulation of the tunnel construction process, with the tunnel buried by soft and weak surrounding rock (V class) at shallow (15m) and deep (550m), this paper analyzes the impact of the M-C and D-P yield criterions on surrounding rock’s displacement, stress, strain effects, and proposes the appropriate yield criterion for the simulation of shallow and deep soft and weak rock tunnel construction and for tunnel surrounding rock stability analysis.